save a few bits by using a 1 bit flag to indicate if a node has data attachments or note.  in the majority case we will use 1 bit instead of 1 byte for a var length integer showing 0.
remove bytes that I thought were bits...
smarter encoding scheme for nodes.  do not need note count and bits if nodedb is null
Merge branch 'sparsepage' of https://github.com/addthis/hydra into sparsepage
trying to protect against strange encoding/decoding errors in ConcurrentKeyTopper